MOLECULAR DETECTION OF DIOSCOREA ALATA BACILLIFORM VIRUS (DABV) ON YAM LEAF SAMPLES AND MEALY BUGS ON YAM FIELDS IN NORTH CENTRAL NIGERIA

Abstract

A survey was conducted in August 2017, in five States of North Central Nigeria, namely; Benue, Kwara, Kogi, Niger and Nassarawa States, to determine the presence of Dioscorea alata bacilliform Virus(DBaV) from yam leaf and mealy bug insect samples collected from yam fields in the study areas. Polymerase Chain Reaction (PCR) of DaBV was conducted on both the yam leaf samples and mealy bugs insect collected. PCR amplified products were analysed using sequence and Phylogeny. The Result showed that all the leaf samples tested positive for DaBV. While Sixty-one percent (61%) of the mealy bug samples tested positive for DaBV. Group one of the sequences showed 99% nucleotide identity to themselves while another group showed 88% nucleotide identity. These two (2) groups of sequences were closely related to Planococcus ficus and P. minor. Two of the sequences (BRK1 and K1) were clustered in the same group with Rastrococcus invadens and P. marginatus respectively. The two new sequences (ZM1 and GB1) appeared to be an out group of the Plan ococcus species and shared 99% nucleotide identity to themselves. The findings of this study proved that, there is the presence of DaBV in the study areas. Therefore, continue monitoring of mealy bug populations is also required, so as to reduce ormaintain its population in the surveyed areas. Further studies should be carried out to characterize the viral diversity by sequencing for thorough understanding of more existing virus strains and other mealy bug species that are likely infecting yam in the study areas; this is for increase yam productivity in the surveyed areas.